Description

Thiol-dPEG®12-acid, product number QBD-10850, is a single molecular weight, discrete-length polyethylene glycol (dPEG®) PEGylation reagent. One end of the medium-length (39 atoms, 46.8 Å) dPEG® linker terminates in a sulfhydryl (thiol) group, while a propionic acid moiety terminates the opposite end. The thiol end of the molecule forms dative bonds with gold, thioether bonds with maleimide and bromoacetate groups, and disulfide bonds with other sulfhydryl groups. The propionic acid group reacts with amines to form amide bonds. Alternatively, if it is left unreacted, the propionic acid group provides a negative charge to the conjugated molecule or modified surface.

Numerous scientific publications attest to the benefits of Thiol-dPEG®12-acid, including the following applications:
Assaying protease by using fluorescence quenching with gold nanoparticles;
Enhancing transfection efficiency;
Modulating glucose transport with gold nanoparticles;
Developing multiplexed bioassays on semiconductor gold nanocrystals;
Developing spectroscopy applications; and,
Detecting cancer through a FRET-based, NIR-activated system that uses gold nanoparticles.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Gold nanoparticle-based fluorescence quenching via metal coordination for assaying protease activity. Se Yeon Park, So Min Lee, Gae Baik, Kim and Young-Pil Kim. Gold Bull. 2012, 45 pp 213–219. October 25, 2012. DOI 10.1007/s13404-012-0070-9.

Systemically probing the bottom-up synthesis of AuPAMAM conjugates for enhanced transfection efficiency. Elizabeth R. Figueroa, Stephen Yan, Nicolette K. Chamberlain-Simon, Adam Y. Lin, Aaron E. Foster, and Rebekah A. Drezek. Journal of Nanobiotechnology. 2016, 14 (24). March 31, 2016. DOI: 10.1186/s12951-016-0178-9.

Modulating the Glucose Transport by Engineering Gold Nanoparticles. Sanjib Bhattacharyya, Krishna Kattel, and Franklin Kim. Journal of Nanomedicine and Biotherapeutic Discovery. 2016, 6 (1) pp 1-5. April 30, 2016. DOI: 10.4172/2155-983X.1000141.

Use of semiconductor nanocrystals to encode microbeads for multiplexed analysis of biological samples. Mikhail A Berestovoy, Regina S Bilan, Victor Krivenkov, Igor Nabiev, and Alyona Sukhanova. IOP Science. 2017, 784 (1) pp 1742-6596. March 15, 2017. DOI: 10.1088/1742-6596/784/1/012012.

Spectroscopy Based Approaches for Detection of Ions, Alpha-L-Fucosidase, and Singlet Oxygen. Eric Waidely. University of Miami Scholarly Repository. 2017, pp 1-113. May 3, 2017. http://scholarlyrepository.miami.edu/oa_dissertations/1842.

Near-Infrared-Activated Fluorescence Resonance Energy Transfer-Based Nanocomposite to Sense MMP2-Overexpressing Oral Cancer Cells. Yung-Chieh Chan, Ming-Hsien Chan, Chieh-Wei Chen, Ru-Shi Liu, Michael Hsiao, and Din Ping Tsai. ACS Omega. 2018,3 (2) pp. 1627-1634. February 8, 2018. DOI: 10.1021/acsomega.7b01494.

Signal enhancement of optical immunosensing by gold nanoparticles. Yuan Xintong. Nanyang Technological University, School of Material Science and Engineering Thesis for the degree of Master of Engineering. 2015, pp 1-74.

Biofunctionalized Polyelectrolyte Microcapsules Encoded with Fluorescent Semiconductor Nanocrystals for Highly Specific Targeting and Imaging of Cancer Cells. Galina Nifontova, Daria Kalenichenko, Maria Baryshnikova, Fernanda Ramos Gomes, Frauke Alves, Alexander Karaulov, Igor Nabiev, and Alyona Sukhanova. Advances on Applications of Optics and Photonics – Selected Papers from the 4th International Conference on Applications of Optics and Photonics, AOP2019. November 8, 2019. DOI: 10.3390/photonics6040117

NEW FRONTIERS FOR TRIPLE NEGATIVE BREAST CANCER DETECTION AND TREATMENT: FROM MECHANICAL BIOMARKERS TO SPECIFIC NANOPARTICLE ENTRY FOR ROBOTICALLY CONTROLLED LASER-INDUCED HYPERTHERMIA. Vanessa Uzonwanne. Worchester Polytechnic Institute. 2022. May 22, 2022.

SCORe: SARS-CoV-2 Omicron Variant RBD-Binding DNA Aptamer for Multiplexed Rapid Detection and Pseudovirus Neutralization. Lucy F. Yang, Nataly Kacherovsky, Joey Liang, Stephen J. Salipante, and Suzie H. Pun. Anal. Chem. 2022, 94, 37, 12683–12690. https://doi.org/10.1021/acs.analchem.2c01993

Description

MAL-dPEG®11-Lipoamide, product number QBD-10819, is a heterobifunctional crosslinker functionalized with a maleimidopropyl group and a lipoic acid moiety on opposite ends of a medium-length (49 atoms, 59.3 Å), single molecular weight, discrete PEG (dPEG®) crosslinker. The lipoic acid moiety forms dative bonds with gold, silver, and other metals and can be used to coat or passivate metal surfaces. The maleimide group forms stable thioether bonds with free thiols and can be used to immobilize a sulfhydryl-containing biomolecule such as a peptide or antibody fragment to a metal surface through the dPEG®-lipoamide linkage. The flexible, non-immunogenic, hydrophilic dPEG® linker adds water solubility and increases the conjugate’s hydrodynamic volume.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pp. 188-190, 458-497, 924-935.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Focal adhesion regulation through microcontact printing of protein nanoparticles on self-assembled monolayers for cell guidance. Albert Martinez Moreno. DUGiDocs. 2016, June 1, 2016. DOI: http://hdl.handle.net/10256/12960.

Description

MAL-dPEG®3-Lipoamide, product number 10817, is a heterobifunctional crosslinker functionalized with a maleimidopropyl group and a lipoic acid moiety on opposite ends of a short (27 atoms, 31.1 Å), single molecular weight, discrete PEG (dPEG®) crosslinker. The lipoic acid moiety forms dative bonds with gold, silver, and other metals and can be used to coat or passivate metal surfaces. The maleimide group forms stable thioether bonds with free thiols and can be used to immobilize a sulfhydryl-containing biomolecule such as a peptide or antibody fragment to a metal surface through the dPEG®-lipoamide linkage. The flexible, non-immunogenic, hydrophilic dPEG® linker adds water solubility and increases the conjugate’s hydrodynamic volume.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pp. 188-190, 458-497, 924-935.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Focal adhesion regulation through microcontact printing of protein nanoparticles on self-assembled monolayers for cell guidance. Albert Martinez Moreno. DUGiDocs. 2016, June 1, 2016. DOI: http://hdl.handle.net/10256/12960.

Description

Lipoamido-dPEG®12-TFP ester, product number QBD-10814, is a single molecular weight, discrete PEG (dPEG®) modification reagent. The product consists of alpha-lipoic acid and a 2,3,5,6-tetrafluorophenyl (TFP) ester on opposite ends of a medium-length (48 atoms) dPEG® spacer. The lipoic acid group forms two (2) coordinate covalent bonds (dative bonds) with metal, especially gold and silver. The TFP ester reacts with free amines to form amide bonds. Applications for this product include peptide or protein immobilization on metal surfaces, the formation of self-assembled monolayers (SAMs) on metal surfaces, and sensor development.

Lipoic acid, also known as α-lipoic acid and thioctic acid, is a naturally occurring antioxidant that functions as a cofactor in several enzyme systems. It consists of a dithiolane ring (a five-membered ring containing a disulfide) attached to a pentanoic acid group. As a bidentate thiol ligand, lipoic acid forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface.

When using this product, it is typical to begin with the conjugation of the carboxyl end of the dPEG® to an amino group to form an amide bond. TFP esters optimally react with amines at pH 7.5 – 8.0. As documented in the scientific literature, TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters.

After reacting the TFP ester end of the molecule, the lipoic acid end of the dPEG® linker can be reacted with metals such as gold or silver. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will reduce lipoic acid to DHLA rapidly.

Lipoamido-dPEG®12-TFP ester dissolves in water or aqueous buffer and organic solvents. Stock solutions in water or aqueous buffer do not have long-term stability and should be used immediately. For stock solutions with long-term stability, we recommend dry (over 3 Å molecular sieves) water-miscible solvents such as N,N-dimethylacetamide (DMAC) or acetonitrile. Unused stock solutions in dry organic solvents should be stored at -20°C or colder.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Lipoamido-dPEG®24-acid, product number QBD-10811, is a single molecular weight, discrete PEG (dPEG®) surface modification reagent for metal surfaces, especially gold and silver. The hydrophilic dPEG®24 spacer is 85 atoms (99 Å) long. The lipoamide moiety rapidly forms stable dative bonds with gold or silver. Using a carbodiimide such as EDC and an acylating agent such N-hydroxysuccinimide (NHS), the propionic acid group will react with free amines to form amide bonds. The water-soluble, non-immunogenic dPEG® spacer adds hydrodynamic volume to conjugates made with this product. For circulating nanoparticles, the increased hydrodynamic volume reduces or eliminates opsonization and facilitates a longer circulation time in vivo.

Lipoic acid, also known as thioctic acid and alpha-lipoic acid (ALA), is an organosulfur compound used by cells as an essential cofactor. The sulfur atoms at positions C6 and C8 form a disulfide bond in a five (5)-membered ring. Like other thiol products, lipoic acid readily forms dative bonds with gold, silver, and other metals. Because two dative bonds form for each molecule of lipoic acid, the thiol-metal dative bond is more stable than dative bonds formed with compounds containing one free thiol atom. Lipoic acid exists typically in an oxidized (closed ring) state. It is readily reduced to an open ring state called dihydrolipoic acid (DHLA) using tris(2-carboxyethyl)phosphine (TCEP) or other reducing agents.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pp. 188-190, 458-497, 924-935.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Compact Biocompatible Quantum Dots Functionalized for Cellular Imaging. Wenhao Liu, Mark Howarth, Andrew B. Greytak, Yi Zheng, Daniel G. Nocera, Alice Y. Ting, and Moungi G. Bawendi. J. Am. Chem. Soc. 2008, 130 (4) pp 1274–1284. January 5, 2008. DOI: 10.1021/ja076069p.

Description

Lipoamido-dPEG®8-acid, product number QBD-10806, is a single molecular weight, discrete PEG (dPEG®) surface modification reagent for metal surfaces, especially gold and silver. The hydrophilic dPEG®8 spacer is 36 atoms (41.2 Å) long. The lipoamide moiety rapidly forms stable dative bonds with gold or silver. Using a carbodiimide such as EDC and an acylating agent such N-hydroxysuccinimide (NHS), the propionic acid group will react with free amines to form amide bonds. The water-soluble, non-immunogenic dPEG® spacer adds hydrodynamic volume to conjugates made with this product. For circulating nanoparticles, the increased hydrodynamic volume reduces or eliminates opsonization and facilitates a longer circulation time in vivo.

Lipoic acid, also known as thioctic acid and alpha-lipoic acid (ALA), is an organosulfur compound used by cells as an essential cofactor. The sulfur atoms at positions C6 and C8 form a disulfide bond in a five (5)-membered ring. Like other thiol products, lipoic acid readily forms dative bonds with gold, silver, and other metals. Because two dative bonds form for each molecule of lipoic acid, the thiol-metal dative bond is more stable than dative bonds formed with compounds containing one free thiol atom. Lipoic acid exists typically in an oxidized (closed ring) state. It is readily reduced to an open ring state called dihydrolipoic acid (DHLA) using tris(2-carboxyethyl)phosphine (TCEP) or other reducing agents.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pp 188-190, 458-497, 924-935.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Site-Specific Conjugation of Antibody on Gold Nanoparticle Surface for One-Step Diagnosis of Prostate Specific Antigen with Dynamic Light Scattering. Nur Mustafaoglu, Tanyel Kiziltepe, and Basar Bilgicer. Nanoscale. 2017, pp 1-32. May 18, 2017. DOI: 10.1039/C7NR03096G.

Single-wavelength-excited flurogenic nanoprobe for accurate realtime ratiometric analysis of broad pH fluctuations in mitophagy. Xin Zhang, Juan Chen, Jiwen Hu, Anna du Rietz, Xiongyu Wu, Ruilong Zhang, Zhongping Zhang, Kajsa Uvdal & Zhangjun Hu. SpringerLink. 2022. May 11, 2022. https://doi.org/10.1007/s12274-022-4325-3.

Description

Lipoamido-dPEG®4-acid, product number QBD-10806, is a single molecular weight, discrete PEG (dPEG®) surface modification reagent for metal surfaces, especially gold and silver. The hydrophilic dPEG®4 spacer is 24 atoms (27.5 Å) long. The lipoamide moiety rapidly forms stable dative bonds with gold or silver. Using a carbodiimide such as EDC and an acylating agent such N-hydroxysuccinimide (NHS), the propionic acid group will react with free amines to form amide bonds. The water-soluble, non-immunogenic dPEG® spacer adds hydrodynamic volume to conjugates made with this product. For circulating nanoparticles, the increased hydrodynamic volume reduces or eliminates opsonization and facilitates a longer circulation time in vivo.

Lipoic acid, also known as thioctic acid and alpha-lipoic acid (ALA), is an organosulfur compound used by cells as an essential cofactor for several enzymes in aerobic respiration. The sulfur atoms at positions C6 and C8 form a disulfide bond in a five (5)-membered ring. Like other thiol products, lipoic acid readily forms dative bonds with gold, silver, and other metals. Because two dative bonds form for each molecule of lipoic acid, the thiol-metal dative bond is more stable than dative bonds formed with compounds containing one free thiol atom. Lipoic acid exists typically in an oxidized (closed ring) state. It is readily reduced to an open ring state called dihydrolipoic acid (DHLA) using tris(2-carboxyethyl)phosphine (TCEP) or other reducing agents.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pp. 188-190, 458-497, 924-935.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Site-Specific Conjugation of Antibody on Gold Nanoparticle Surface for One-Step Diagnosis of Prostate Specific Antigen with Dynamic Light Scattering. Nur Mustafaoglu, Tanyel Kiziltepe, and Basar Bilgicer. Nanoscale. 2017, pp 1-32. May 18, 2017. DOI: 10.1039/C7NR03096G.

Gastrointestinal Bioavailability of 2.0 nm Diameter Gold Nanoparticles. Candice A. Smith, Carrie A. Simpson, Ganghyeok Kim, Carly J. Carter, and Daniel L. Feldheim. ACS Nano. 2013, 7 (5) pp 3991–3996. April 21, 2013. DOI: 10.1021/nn305930e.

Compact Biocompatible Quantum Dots Functionalized for Cellular Imaging. Wenhao Liu, Mark Howarth, Andrew B. Greytak, Yi Zheng, Daniel G. Nocera, Alice Y. Ting, and Moungi G. Bawendi. J. Am. Chem. Soc. 2008, 130 (4) pp 1274–1284. January 5, 2008. DOI: 10.1021/ja076069p.

Description

Lipoamido-dPEG®36-TFP ester, product number QBD-10644, is a single molecular weight, discrete PEG (dPEG®) modification reagent. The product consists of alpha-lipoic acid and a 2,3,5,6-tetrafluorophenyl (TFP) ester on opposite ends of a long (120 atoms) dPEG® spacer. The lipoic acid group forms two (2) coordinate covalent bonds (dative bonds) with metal, especially gold and silver. The TFP ester reacts with free amines to form amide bonds. Applications for this product include peptide or protein immobilization on metal surfaces, the formation of self-assembled monolayers (SAMs) on metal surfaces, and sensor development.

Lipoic acid, also known as α-lipoic acid and thioctic acid, is a naturally occurring antioxidant that functions as a cofactor in several enzyme systems. It consists of a dithiolane ring (a five-membered ring containing a disulfide) attached to a pentanoic acid group. As a bidentate thiol ligand, lipoic acid forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface.

When using this product, it is typical to begin with the conjugation of the carboxyl end of the dPEG® to an amino group to form an amide bond. As documented in the scientific literature, TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters. TFP esters optimally react with amines at pH 7.5 – 8.0.

After reacting the TFP ester end of the molecule, the lipoic acid end of the dPEG® linker can be reacted with metals such as gold or silver. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will reduce lipoic acid to DHLA rapidly.

Lipoamido-dPEG®36-TFP ester dissolves in water or aqueous buffer and organic solvents. Stock solutions in water or aqueous buffer do not have long-term stability and should be used immediately. For stock solutions with long-term stability, we recommend dry (over 3 Å molecular sieves) water-miscible solvents such as N,N-dimethylacetamide (DMAC) or acetonitrile. Unused stock solutions in dry organic solvents should be stored at -20°C or colder.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Lipoamido-dPEG®24-TFP ester, product number QBD-10643, is a single molecular weight, discrete PEG (dPEG®) modification reagent. The product consists of alpha-lipoic acid and a 2,3,5,6-tetrafluorophenyl (TFP) ester on opposite ends of a long (84 atoms) dPEG® spacer. The lipoic acid group forms two (2) coordinate covalent bonds (dative bonds) with metal, especially gold and silver. The TFP ester reacts with free amines to form amide bonds. Applications for this product include peptide or protein immobilization on metal surfaces, the formation of self-assembled monolayers (SAMs) on metal surfaces, and sensor development.

Lipoic acid, also known as α-lipoic acid and thioctic acid, is a naturally occurring antioxidant that functions as a cofactor in several enzyme systems. It consists of a dithiolane ring (a five-membered ring containing a disulfide) attached to a pentanoic acid group. As a bidentate thiol ligand, lipoic acid forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface.

When using this product, it is typical to begin with the conjugation of the carboxyl end of the dPEG® to an amino group to form an amide bond. As documented in the scientific literature, TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters. TFP esters optimally react with amines at pH 7.5 – 8.0.

After reacting the TFP ester end of the molecule, the lipoic acid end of the dPEG® linker can be reacted with metals such as gold or silver. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will reduce lipoic acid to DHLA rapidly.

Lipoamido-dPEG®24-TFP ester dissolves in water or aqueous buffer and organic solvents. Stock solutions in water or aqueous buffer do not have long-term stability and should be used immediately. For stock solutions with long-term stability, we recommend dry (over 3 Å molecular sieves) water-miscible solvents such as N, N-dimethylacetamide (DMAC) or acetonitrile. Unused stock solutions in dry organic solvents should be stored at -20°C or colder.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Lipoamido-dPEG®8-TFP ester, product number QBD-10642, is a single molecular weight, discrete PEG (dPEG®) modifier of gold and silver surfaces, for example, on nanoparticles. The lipoic acid moiety on one end of the 36-atoms-long dPEG® spacer forms dative bonds with metals like gold and silver. The TFP ester reacts with free amines to form free amines, optimally in the pH range 7.5 – 8.0. The distance from the disulfide bond in the lipoic acid ring to the carbonyl carbon adjacent to the 2,3,5,6-tetrafluorophenol (TFP) ester, the distance is 36 atoms (42.7 Å). Applications for this product include creating self-assembled monolayers (SAMs) on metal surfaces and crosslinking and immobilizing peptides and proteins to the surfaces of metal nanoparticles.

Lipoic acid, also known as alpha-lipoic acid, α-lipoic acid, and thioctic acid, consists of a five-membered ring containing a disulfide attached to a pentanoic acid group. As a naturally occurring antioxidant, lipoic acid functions as a cofactor in several enzyme systems. It is a bidentate thiol ligand that forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will rapidly reduce lipoic acid to DHLA.

TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters. The superiority of PEG-TFP esters over NHS esters is documented in the scientific literature. When using this product, it is typical to conjugate the carboxyl end of the dPEG® to an amine to form an amide bond before forming a dative bond between a metal surface and the lipoic acid moiety of Lipoamido-dPEG®8-TFP ester. The TFP ester reacts optimally at pH 7.5 – 8.0, but it will also react with amines at pH values above and below this range.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Surface-Assisted Affinity Purification Mass Spectrometry (SAAP-MS)for Determination of Enzyme Activities. Yang. Hyojik. UC Riverside Electronic Theses and Dissertations. 2016, pp 1-221. June 2016. http://escholarship.org/us/item/2qv796zz.